This proposal describes a research program designed to determine the factors that contribute to the familial aggregation of specific language disorders in families. The proposed research will identify those clinical measures necessary for the diagnosis of specific language disorders in adults. These measures will then be combined with a set of existing measures for children to determine the presence of specific language impairment (probands). Pedigrees for specific language impairment will be generated. Using these pedigrees, complex segregation analysis will be performed to determine whether there is a major genetic locus, as well as the extent to which genetic heterogeneity is present in these families showing a high density of specific language disorder. The DNA and leukocytes will be recovered from this blood for the purposes of future analysis. This research is concerned with improving our understanding of the causes of a form of developmental language disorder in which the primary manifestation is a deficit in language development in spite of apparently normal auditory sensitivity and nonverbal intelligence. By determining the basis of this familial aggregation, improved early identification, and prevention may be possible.